[unreadable] We propose to develop a clinically usable robotic cutter of the next generation that combines the advantages of the surgical navigation and robotic actuation into a conceptually new device. The device can be classified as a semi-active robotic tool, and fills in the niche between the surgical navigation and active robotics. The basic idea of the proposed device, named Precision Freehand Sculptor (PFS) comprises of an intelligent cutting tool that cuts when it is inside the volume designated for cutting, and stops cutting when it is placed outside of that volume, based on the sensing of its position relative to the target bone. The concept was received with great enthusiasm by both surgeons and researcher when it was recently introduced at several scientific meetings. The device works with surgical navigation systems and it shares the position sensing and updating with the navigation system, while it uses the mechanism controls characteristic of robotic devices to control the action. Because it is handheld, it can be much smaller than typical surgical robots, and because it does not involve specific path planning, it is much more flexible and adaptable to the operating room conditions. Since it can be made much smaller than the conventional robots, PFS could play an important role in supporting minimally invasive surgical procedures. [unreadable] [unreadable] Our initial focus will be on minimally invasive knee arthroplasty, in particular on Patello-femoral Arthroplasty (PFA), which is currently lacking adequate instrumentation and is often done free-hand. The specific goals of the Phase I of this grant are arranged in three categories: (1) Develop PFS control software and test and improve accuracy of the achieved surface. The accuracy of the surface cut by the PFS is critical to the success of the implant placement. The goal is to achieve the accuracy of 1 mm. (2) Develop the user interface software suitable for operating room (OR) environment; and (3) Develop the PFS mechanism for small incision Patello-femoral Arthroplasty. The ultimate goal is of the project is to create operating room - friendly tool that will enable more accurate surgical bone shaping in the minimally invasive surgical environment. [unreadable] [unreadable]